In an electronic device containing a display system, a display controller typically receives information from a processor or memory storage device and transmits the information to a display device. The information typically consists of rows of pixels configured to display images, such as pictures, text, and frames of video, stored in the memory storage device. For color displays, each pixel contains red, green, and blue components that may vary in intensity to form specific colors. For example, a 12-bit pixel may form 4,096 (212) different colors with four bits representing the red component, four bits representing the green component, and four bits representing the blue component. Each bit may be either of the two binary digits 0 or 1. A 16-bit pixel may form 65,536 (216) different colors with five bits representing each red and blue component, and six bits representing the green component. A 24-bit pixel may form 16,777,216 (224) different colors with eight bits representing each red, green, and blue component, and so on.
Display devices capable of displaying many colors are visually pleasing to a user. Accordingly, users may prefer a display system containing 16-bit pixels over 8-bit pixels and a display system containing 24-bit pixels over 16-bit pixels. However, using pixels with a large storage size may not be possible in all display systems. Display systems that use large-storage-size pixels may require a large bandwidth, a large memory storage capacity, long image processing times, and increased power consumption. In portable electronic devices in which low power consumption, low memory storage requirements, and low bandwidth requirements are highly desirable, display systems using large pixel storage sizes may not be appropriate.
One solution to this problem has been to remove least significant bits from color components in pixels to reduce pixel storage size at the expense of image quality. The least significant bits in a color component have less effect on the color of the pixel than the most significant bits. However, this technique may noticeably reduce image quality when displaying color gradients, which are gradual color shifts in an image. Color gradients displayed using this technique may appear to have undesirable, abrupt, and blocky color changes rather than smooth, gradual changes.